RAID Technology

Various Implementations of RAID Types with EMC Symmetrix / DMX and Clariion Technology.

RAID (Redundant Array of Inexpensive or Independent Disk)

RAID 0 – Striped Disk Array without Fault Tolerance: Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails then all data in the array is lost.

RAID 1 – Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks.

RAID 5 – Block Interleaved Distributed Parity: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance. Level 5 is one of the most popular implementations of RAID.

RAID 0 + 1 – A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.

RAID S (3 + 1): EMC Symmetrix / DMX disk arrays use an alternate, proprietary method for parity RAID that they call RAID-S. Three Data Drives (X) along with One Parity device. RAID-S is proprietary to EMC but seems to be similar to RAID-5 with some performance enhancements as well as the enhancements that come from having a high-speed disk cache on the disk array.

RAID S (7+1): EMC DMX disk arrays use an alternate, proprietary method for parity RAID that they call RAID-S. Seven Data Drives (X) along with One Parity device. RAID-S is proprietary to EMC but seems to be similar to RAID-5 with some performance enhancements as well as the enhancements that come from having a high-speed disk cache on the disk array.

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The opinions expressed here are my - StorageNerve opinions. This blog and the content published here is not read or approved in advance by my employer (Accenture) or clients and does not reflect their views and opinions.